2,000 years of evolution has made Britons taller and blonder

A new technique has been used to track changes in the genome of Britons over the last 2,000 years – and we've become taller, blonder and more likely to have blue eyes.

The technique, developed by geneticists at Stanford University and detailed in a paper hosted on bioRxiv, tracked changes in the genomes of over 3,000 Britons involved in UK10K, a project designed to help researchers detect rare genetic variants.

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Previous genomic analyses had mainly focused on natural selection over larger time spans, and attempts to track more recent changes have also "relied on ancient human DNA", according to Nature.

The new technique is able to both "narrow this window" and pinpoint exact traits such as height, hair and eye colour by calculating a 'singleton density score', which indicates how dense the nearby population for unique mutations is for any given genome.

By analysing which alleles are most dense, the researchers were then able to isolate the specific traits that had been selected over the last 2000 years.

The analysis showed that the British population was now more likely to have blonde hair and blue eyes, be taller, have larger head and hip sizes and have an improved ability to digest milk. Women are also more likely to start menstruation later into adolescence.

The team now hope to use their method, which uses statistical analysis to examine whole genome sequences, on other populations – which could reveal whether similar traits are emerging across other groups of people.